1. The Journal of Arthroplasty Vol. 13 No. 2 1998
Factors Affecting Length of Stay and Need for
Rehabilitation After Hip and Knee Arthroplasty
George Forrest, MD,* Marc Fuchs, MD,J- Ariel Gutierrez,{
and James Girardy, MD§
Abstract: The purpose of this study was to determine the factors that predict the
length of stay on a surgical service after total hip or knee arthroplasty and the factors
that predict whether a patient will require admission to a rehabilitation unit before he
or she is ready to return home. The authors reviewed the records of all patients
admitted to the Albany Medical Center for elective total hip or total knee arthroplasty
in 1995. The study looked for correlations of patients' age, sex, marital status, body
mass index, and comorbid illnesses with length of stay on the surgical service and
need for inpatient rehabilitation. The only factor that correlated with length of stay
on the surgical unit was age. The factors that correlated with the need for inpatient
rehabilitation were age and diabetes mellitus. K e y words: hip arthroplasty, knee
arthroplasty, length of stay, rehabilitation.
Hip a n d k n e e joint arthroplasties are the best treat- 1974, Coventry et al. reported protocols for m a n a g e -
m e n t s for patients with a d v a n c e d arthritis that is m e n t of hip arthroplasties at the M a y o Clinic that
painful, limits function, a n d does n o t r e s p o n d to r e c o m m e n d e d discharge on day 21 [1]. In 1990,
conservative care. In p r o p e r l y selected patients, the Harris and Sledge reported a n average length of stay
p r o c e d u r e s are safe a n d effective. The mortality rate of 9 - 1 0 days [2,3]. Current protocols call for dis-
is less t h a n one half of 1%. The rate of serious charge on the fifth postoperative day. Protocols of
medical complications (myocardial infarction, p n e u - streamlined care w i t h short length of stay o n acute
monia, p u l m o n a r y embolus, renal failure) is less surgical units assume that most patients will be ready to
t h a n 2%. The rate of local complications, such as r e t u m directly to their homes or the homes of family or
peripheral n e r v e injury, w o u n d infection, a n d peri- friends at the time of discharge but that some patients
prosthetic fracture, is less t h a n 5 %. The success rate will require admission to a rehabilitation unit.
in reducing pain and i m p r o v i n g function is greater M o r r o w - H o w e l l and Proctor n o t e d that the basis
t h a n 9 0 % [1-3]. on w h i c h decisions are m a d e as to w h i c h patients
The n u m b e r of patients a d m i t t e d for total joint are discharged to h o m e and w h i c h to rehabilitation
arthroplasty is increasing yearly. The length of time is not clear [4]. Several investigators h a v e looked at
patients stay in the hospital is steadily decreasing. In the factors that w o u l d predict the n e e d for extensive
rehabilitation. Age, sex, race, insurance, comorbid
illnesses, type of arthritis, operative complications,
From the *Department of PhysicaI Medicine and Rehabilitation and
the §Department of Medicine, Albany Medical College; -~Capital Region and living situation h a v e all b e e n cited as factors
Orthopedic Associates; and ¢Rensselaer Polytechnic Institute, Albany, that can d e t e r m i n e w h e t h e r a patient can receive
New York. a d e q u a t e rehabilitation at h o m e or will require
Supported by the David Cornell Lawrence Memorial Endow-
ment Fund. transfer to a rehabilitation unit {4-8].
Address correspondence to George Forrest, MD, Department of The p u r p o s e of this study was to review the data
Physical Medicine and Rehabilitation, Albany Medical Center, 43 f r o m p r o c e d u r e s done at the Albany Medical Center
New Scotland Avenue, Albany, NY 12208.
Copyright © 1998 Churchill Livingstone. to d e t e r m i n e if at the time the surgery is planned, it
0883-5403l 1302-000955.00/0 is possible to predict w h e t h e r a patient is likely to be
186

2. Length of Stay/Need for Rehabilitation AfterTHA/TKA • Forrest et al. 187
discharged home or to require admission to a in the past medical history included history of prior
rehabilitation unit. joint arthroplasty, organic heart disease (coronary
artery disease, myocardial infarction, congestive
Materials and Methods heart failure, valvular heart disease, arrhythmia),
asthma, chronic obstructive pulmonary disease
The Albany Medical Center is a 620-bed hospital (COPD), diabetes, stroke, Parkinson's disease, and
in the Capital District of New York State. It is the rheumatoid arthritis or other systemic collagen
main teaching hospital of the Albany Medical Col- vascular disease. Body mass index (BMI) was calcu-
lege. Full-time faculty, physicians in private prac- lated based on the patient's height and weight
tice, and physicians who work for a staff model (BMI = weight in kilograms divided by height in
health maintenance organization have privileges to meters squared).
practice orthopaedic surgery at the hospital. One hundred forty-seven patients were admitted
Patients are seen on the first postoperative day by for elective joint arthroplasty. Twenty-one were
physical therapy. Before being discharged home, excluded from the study because their records
patients are expected to be able to transfer from either could not be located or were incomplete
supine to sitting and from sitting to standing and to (height and weight were not obtained). There was 1
walk household distances with a walker or crutches. mortality; that patient was excluded from the study.
Patients are expected to be independent in dressing The data were analyzed using the Statistical Analy-
and bathroom activities or to be able to perform sis System. Pearson's correlation coefficient was
these activities with help that is available at home. used to look for significant correlations between
Patients who have had hip arthroplasties are ex- age, sex, marital status, premorbid conditions, and
pected to understand appropriate precautions to BMI with length of stay on the surgical service and
prevent dislocation of the prosthesis, and patients with place of discharge.
who have had knee arthroplasties are expected to
have 90 ° of range of motion or to be making Results
progress sufficient to indicate that they will achieve
that range with in-home therapy. All insurers in the One hundred and twenty-five patients were in-
Capital District of upstate New York provide for cluded in the study. Eleven surgeons performed the
in-home nursing if necessary and in-home physical operations. There were 63 hip arthroplasties and 62
therapy for at least 60 days if necessary. Medicare knee arthroplasties. The average length of stay on
and Medicaid provide for home health aides as the surgical service was 6.4 days. One hundred one
necessary to assist in personal care such as bathing, patients were discharged to their homes or the
dressing, and meal preparation. Private insurance homes of friends or relatives, and 24 were admitted
policies vary as to whether they provide home to rehabilitation units. The demographic features of
health aides. Patients must rely on friends or family the entire group of patients in the study are listed in
for help with household cleaning, transportation, Table 1. The demographic features of the patients
and shopping. The decision as to whether patients who were admitted to rehabilitation units are listed
are discharged home or transferred for rehabilita- in Table 2.
tion is made by the patient's surgeon with input The only characteristic that had a statistically
from the nursing staff, the patient's therapists, significant correlation with length of stay on the
discharge planning, the patient, and the patient's surgical floor was age (Table 3). The only character-
family. Most third-party payors other than Medicare
and Medicaid require prior authorization for fund-
ing of admissions to rehabilitation units.
T a b l e 1. D e m o g r a p h i c s of Total P a t i e n t G r o u p
We reviewed the medical records of all patients
admitted to the Albany Medical Center in 1995 for n 125
elective hip and knee joint arthroplasty. Patients Average age (y) 63.6
Women 56.8%
who underwent joint arthroplasty after fracture or Men 43.2%
resection of neoplasms were excluded from the Married 48%
study. The information obtained from each chart Body mass index 30.7
Chronic obstructive pulmonary disease/asthma 15 %
included the patient's age, sex, height, weight, past Organic heart disease 30%
medical history, marital status, surgeon, operation Diabetes 7%
performed, postoperative complications, length of Rheumatoid arthritis 7%
History of prior joint arthroplasty 38%
stay on surgical service, and place of discharge (to Admitted for revision of prior joint arthroplasty 14%
home or to rehabilitation). The problems recorded

3. 188 The Journal of Arthroplasty Vol. 13 No. 2 February 1998
T a b l e 2. Demographics of Patients Who Went T a b l e 4. C o r r e l a t i o n W i t h Discharge to R e h a b i l i t a t i o n
to R e h a b i l i t a t i o n
P Value*
n 24
Average age (y) 70.8 Age (y) .006
Women 75 % Marital status 0
Men 25% Body mass index .06
Married 62% Chronic obstructive pulmonary disease/asthma .6
Body mass index 32.9 Organic heart disease .4
Chronic obstructive pulmonary disease/asthma 21% Diabetes .004
Organic heart disease 38% Rheumatoid arthritis .813
Diabetes 21% Prior joint arthroplasty .06
Rheumatoid arthritis 10 % Revision .32
History of prior joint arthroplasty 46%
Admitted for revision 21% *P values < .05 indicate statistical significance.
E l e v e n s u r g e o n s p e r f o r m e d 125 o p e r a t i o n s . The
istics t h a t h a d a s t a t i s t i c a l l y s i g n i f i c a n t c o r r e l a t i o n
n u m b e r of o p e r a t i o n s p e r s u r g e o n v a r i e d f r o m 38 to
w i t h t h e n e e d for a d m i s s i o n to a r e h a b i l i t a t i o n u n i t
1. T h e p e r c e n t a g e of e a c h s u r g e o n ' s p a t i e n t s w h o
w e r e age a n d d i a b e t e s m e l l i t u s .
w e r e t r a n s f e r r e d to r e h a b i l i t a t i o n v a r i e d f r o m 0 to
T h e a v e r a g e age of t h e t o t a l g r o u p w a s 63.4 y e a r s .
26. T h e r e w a s n o statistical s i g n i f i c a n c e (P = .412)
T h e a v e r a g e a g e of t h e p a t i e n t s w h o w e r e a d m i t t e d
b e t w e e n s u r g e o n a n d t r a n s f e r to r e h a b i l i t a t i o n or
to r e h a b i l i t a t i o n u n i t s w a s 70.8 y e a r s . A l t h o u g h age
b e t w e e n s u r g e o n a n d l e n g t h of stay.
w a s c o r r e l a t e d w i t h t h e n e e d for r e h a b i l i t a t i o n , t h e
T w e n t y - f i v e p e r c e n t of w o m e n i n t h e s t u d y a n d
m a j o r i t y ol e l d e r l y p a t i e n t s w e r e a b l e to b e dis-
i 2 . 5 % of m e n in t h e s t u d y r e q u i r e d t r a n s f e r to
c h a r g e d to h o m e (Table 4). E l e v e n p a t i e n t s w e r e
r e h a b i l i t a t i o n u n i t s (Table 5). B y P e a r s o n ' s c o r r e l a -
m o r e t h a n 80 y e a r s old; 7 w e r e d i s c h a r g e d to h o m e
t i o n coefficient, this d i f f e r e n c e w a s n o t statistically
a n d 4 to r e h a b i l i t a t i o n u n i t s . T h e a v e r a g e l e n g t h of
significant. T h e r e w e r e t h r e e d i f f e r e n c e s in t h e
s t a y o n t h e s u r g i c a l u n i t of t h e p a t i e n t s w h o w e r e
d e m o g r a p h i c d a t a of t h e m e n a n d w o m e n . T h e
d i s c h a r g e d to h o m e w a s 8.2 days.
w o m e n w e r e o l d e r ( m e a n age, 65.4 vs 61.2). T h e
T h e o n l y c o m o r b i d illness t h a t a f f e c t e d p l a c e of
w o m e n w e r e h e a v i e r (BMI, 31.6 vs 29.6 for m e n ) .
discharge was diabetes mellitus. Nine patients had
T h e w o m e n w e r e m u c h less l i k e l y to be m a r r i e d .
diabete's m e l l i t u s . F i v e (55 % ) w e r e d i s c h a r g e d to
T h i r t y - t w o p e r c e n t of w o m e n a n d 7 8 % of m e n in
rehabilitation units. Patients with any combination
the study were married.
of t w o o t h e r p r e m o r b i d illnesses o r o n e o t h e r
B o d y m a s s i n d e x is t h e p a t i e n t ' s w e i g h t in k i l o -
p r e m o r b i d illness a n d o b e s i t y ( B M I > 30) d i d n o t
g r a m s d i v i d e d b y t h e s q u a r e of t h e p a t i e n t ' s h e i g h t
h a v e i n c r e a s e d l e n g t h of s t a y or i n c r e a s e d n e e d for
i n m e t e r s . A p e r s o n w i t h a B M I of 2 7 - 2 9 . 9 is
a d m i s s i o n to r e h a b i l i t a t i o n u n i t s . Statistical a n a l y s i s
c o n s i d e r e d to b e o v e r w e i g h t , a n d o n e w i t h a B M I of
was not done on patients with Parkinson's disease
30 o r greater, to b e o b e s e [9]. As t h e a v e r a g e B M I of
or s t r o k e b e c a u s e t h e n u m b e r of p a t i e n t s w i t h t h e s e
t h e g r o u p w a s 30.7, m o s t of t h e p a t i e n t s w e r e
d i s o r d e r s w a s t o o s m a l l (0, P a r k i n s o n ' s ; 4, s t r o k e ) .
overweight. There were no statistically significant
T a b l e 3. C o r r e l a t i o n With Length of Stay T a b l e 5. Proportion of Patients Sent to R e h a b i l i t a t i o n
o n Surgical Service
No. of No. of Patients
P Value* Surgeon Cases to Rehabilitation
Age (y) .0011 1 29 4
Marital status .77 2 11 1
Body mass index .74 3 38 10
Chronic obstructive pulmonary disease/asthma .88 4 4 0
Organic heart disease .11 5 4 1
Diabetes .21 6 4 0
Rheumatoid arthritis .88 7 15 4
Prior joint arthroplasty .22 8 9 3
Revision .57 9 7 l
Surgeon .15 10 1 0
11 3 0
*P values < .05 indicate statistical significance,

4. Length of Stay/Need for Rehabilitation After THA/TKA • Forrest et al. 189
correlations b e t w e e n BMI and length of stay or f o u n d that the factors that correlated with the n e e d
b e t w e e n BMIs of those discharged to h o m e and for rehabilitation w e r e age, presence of 2 comorbid
those discharged to a rehabilitation unit. W h e n BMI conditions, w h e t h e r the patient lived alone, and
was correlated w i t h all of the other factors looked at level of pain after surgery.
in the study, the only correlation of statistical A m a j o r difference b e t w e e n M u n i n and col-
significance was that patients a d m i t t e d for revision leagues' study a n d this study is that at the University
of a prior arthroplasty w e r e heavier t h a n the group of Pittsburgh, 4 0 % of patients w e r e discharged to
as a w h o l e (P = .0446). rehabilitation units and in this study only 19% of
The rate of complications was low. There was 1 patients were discharged to rehabilitation units.
mortality; a patient h a d a myocardial infarction in This is m o s t likely due to the increasing emphasis on
the perioperative period. That patient was not in- reducing total length of stay, reducing total costs,
cluded in the study, as the p u r p o s e of the study was and providing medical services at h o m e or in the
to look for correlations with length of stay and place outpatient setting rather t h a n in the hospital. The
of discharge. There w e r e a total of 13 d o c u m e n t e d m a j o r similarity b e t w e e n the studies is that age is
postoperative complications. Two patients devel- the factor that has the greatest effect on length of
oped congestive heart failure; l, angina pectoris; stay and the n e e d for extensive rehabilitation. In
and 1, an a r r h y t h m i a . One patient developed a deep this study, patients with cardiac disease a n d / o r
vein thrombosis. One patient h a d a fever, the source p u l m o n a r y disease w h o w e r e acceptable candidates
of w h i c h could not be identified. Two patients h a d for the p r o c e d u r e tolerated it well and did not h a v e
urinary tract infections, and 1 developed urinary increased length of stay or increased n e e d for
retention. One developed cellulitis at an inlrave- admission to rehabilitation units. Patients with rheu-
nous site and 1 developed p n e u m o n i a . One patient matoid arthritis and patients admitted for revisions
developed depression and 2 developed confusion. of prior surgeries did not h a v e increased length of
These patients t e n d e d to stay longer t h a n the group stay or increased n e e d for admission to rehabilita-
as a whole. The average length of stay of these tion units. Patients with diabetes h a d increased
patients was 9.16 days. Six w e r e discharged to h o m e frequency of admission to rehabilitation units. This
a n d 6 to rehabilitation units, a n d 1 was transferred m a y be due to the small sample size or to the
to a psychiatric unit before being discharged to characteristics of that disease, w h i c h m a y include
h o m e . N o n e of these patients was discharged to proximal muscle weakness and peripheral neuropathy.
h o m e in less t h a n i week. We recognize 2 weaknesses in the study. First,
The type of insurance did not s e e m to be a m a j o r marital status m a y not be an adequate indication of
factor in d e t e r m i n i n g w h e t h e r patients w e r e dis- the a m o u n t of assistance a patient can obtain f r o m
charged to rehabilitation units. In the Capital Dis- friends or family after discharge. Second, this was a
trict of New York State, virtually all insurers, w h e t h e r retrospective study that correlated patients' d e m o -
health m a i n t e n a n c e organizations, providers of in- graphics and comorbid illnesses with length of stay
d e m n i t y plans, or providers of coverage secondary and need for rehabilitation. A prospective study that
to Medicare, require authorization prior to admis- looks at level of function prior to surgery m i g h t
sion to a rehabilitation unit. Only patients with provide additional i n f o r m a t i o n t o w a r d a m o d e l that
Medicaid or Medicare/Medicaid can be trans{erred can predict the time and resources necessary to help
f r o m acute care to rehabilitation w i t h o u t s o m e a patient regain function after a hip or k n e e arthro-
oversight f r o m a third-party payor. Of the 7 patients plasty.
w h o h a d Medicaid coverage, 5 w e r e discharged to
h o m e and 2 to rehabilitation. Five patients h a d Acknowledgments
Medicare with Medicaid as a backup, and all w e r e
discharged to h o m e . We t h a n k Michelle Kmieciak and R u t h Cook for
their help with research and p r e p a r a t i o n of the
Discussion manuscript.
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